#include <iostream>
#include <cassert>
#include <string>
#include <typeinfo>
#include <unistd.h>

class Any
{
private:
    class holder
    {
    public:
        virtual ~holder() {}
        virtual const std::type_info &type() = 0;
        virtual holder *clone() = 0;
    };

    template <class T>
    class placeholder : public holder
    {
    public:
        placeholder(const T &val) : _val(val) {}
        // 获取子类对象保存的数据类型
        virtual const std::type_info &type()
        {
            return typeid(T);
        }
        // 针对当前的对象自身，克隆出一个新的子类对象
        virtual holder *clone()
        {
            return new placeholder<T>(_val);
        }

    public:
        T _val;
    };
    holder *_content;

public:
    // 无参构造
    Any() : _content(nullptr) {}
    // 值构造
    template <class T>
    Any(const T &val) : _content(new placeholder<T>(val)) {}
    // 对象构造
    Any(const Any &other) : _content(_content ? other._content->clone() : nullptr) {}
    ~Any()
    {
        delete _content;
    }

    void swap(Any &other)
    {
        std::swap(_content, other._content);
    }

    // 返回子类对象保存的数据指针
    template <class T>
    T *get()
    {
        assert(typeid(T) == _content->type());

        return &((placeholder<T> *)_content)->_val;
    }
    // 赋值运算符重载
    template <class T>
    Any &operator=(const T &val)
    {
        Any(val).swap(*this);
        return *this;
    }
    Any &operator=(const Any &other)
    {
        Any(other).swap(*this);
        return *this;
    }
};

class Test
{
public:
    Test()
    {
        std::cout << "构造" << std::endl;
    }
    Test(const Test &t)
    {
        std::cout << "拷贝构造" << std::endl;
    }

    ~Test()
    {
        std::cout << "析构" << std::endl;
    }
};

int main()
{
    Any a;

    {
        // Any a;
        Test t;
        a = t;
    }

    // a = 10;
    // int *pa = a.get<int>();
    // std::cout << *pa << std::endl;
    // a = std::string("nightcord");
    // std::string *ps = a.get<std::string>();
    // std::cout << *ps << std::endl;
    while (true)
        sleep(1);
    return 0;
}



